Process and machine for thickening pulp



April 29, 1930. J, H 1,756,194

PROCESS AND MACHINE FOR THICKENING PULP Fild Sepq. 4, 1926 Y 2 Sheets-Sheet 1 I NV EN TOR.

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Z2 A TTORNEY.

April 29, 1930. A. J. HAUG 1,756,194

PROCESS AND MACHINE FOR THICKENING PULP Filed Sept. 4, 1926 2 Sheets-Sheet 2' INVENTOR.

A TTORNE Y.

Patented Apr. 29, 1930 ANTON JOSEPH HAUG, OF NASHUA, NEW HAMIPSHIRE PROCESS AND MACHINE FOR THICKENING PULP Application filed September 4, 1926. Serial No. 133,579.

This invention i'elates to processes of and machines for straining or thickening liquids having solid materials suspended therein.

The invention will be herein disclosed as embodied in a machine for thickening paper pulp, it being understood that the term pulp is used in a generic sense to include other materials which the machine is adapted to handle.

Pulp thickeners out surplus Water are widely used to strain in which the solid constit-- uents of the pulp are suspended. The present invention aims to devise a machine which will perform this operation rapidly and efficiently, will be economical of power, will have a large capacity in proportion to its size, and will be economical to manufacture. It is an especially important object of the invention to improve thickeners of the centrifugal type with a view to devising means for removing the thickened pulp continuously and more efficiently from the machine while avoiding any possibility of injury to the screening surface, and to provide a simple and readily operable arrangement whereby the thickness of the pulp on the screening surface can be controlled. The invention also involves a novel method of thickening pulp. The nature of the invention will be readily understood from the following description when read in connection, with the accompanying drawings. and the novel features will be particularly pointed out in the appended claims. In the drawings,

v Figure .1 is a central. vertical, cross-sectional View of the machine constructed in accordance with this invention;

Fig. 2 is a perspective view of a scraper 40 mechanism adapted to be used in the machine shown in Fig. 1;

Fig. 2 is a cross-sectional view through One of the blades of the scraper shown in Fig. 2;

r u I h View showing diagram- Fig. 3 is a cross-sectional view on the line p matically the driving mechanism for the machine.

The machine shown includes a rotary cylindrical screening drum, the screening surface of which preferably consists of a Wire fabric 2 of suitable mesh. The

surface of thisdrum may, however,'be constructed of either perforated or slotted metal plates, or

of any other filtering medium.

suitable foraminous material of This surface on which the thickening action takes place will be herein referred to as the screen or screening surface. One end of the screen 2 is supported on a spider 3, while the on a. ring 4. Between the parts 3 other end is mounted and 4 the screen is supported by a series of thin rings 5'. The

spider 3 and the rings 4 and 5 are all secured together by bolts 6, and they are spaced from each other by spacing 001- lars 7.

In order to support the screening drum for rotation, the spider 3 is mounted fast on a hollow shaft 8 which is supported in bearings 9 and 10, a pulley 12 being secured on the outer end of this shaft so that it may he belted to any convenient source of power.

The material to be thickened is conducted to the spider end of the screening drum by a conduit 13. This material may be supplied from a suitable head box provided with an adjustable wier so that the stock will flow into the machine under just enough head to deliver it at the desired rate. As the incoming pulp approaches the spider 3,

a stationary baffle it strikes plate or distributor 14,

which preferably is curved, as clearly shown in Fig. 1, so that it directs the pulp outwardly toward the screening drum. At this end the drum is provided with a chamber 15 having walls 16 which are inclined toward the screen As the pulp flows into contact with the rapidly revolving surfaces of the drum, this rapid rotary motion is imparted to the pulp and the centrifugal inertia so created in the .ulp causes 17 in the spider 3 it to flow through the apertures and thence into contact with the inner surface of the drum 2. Preferably. this spider is equipped with several blades or impellers imparting the desi 19. Fig. 1, which assist in red rotary motion to the concentrate at the bottom of the screen.

The water is impelled through the screen chiefly due to centrifugal inertia or centrifugal force, this water being caught by the walls of the casing 18 in which the drum is mounted and discharged through a pipe 20 which leads from the bottom of the casing. The solid constituents of the pulp which cannot pass through the screen 2 collect on the inner surface thereof and form a mat or filter bed of thickened pulp. The thickened pulp is removed continuously by a scraper-21 which is mounted inside the screening drum, a suitable clearance space being provided between the edge of the scraper and the screen 2 so that the scraper does not actually come in contact with the screen. This scraper revolves independently of the screening drum, but in the same direction with it and at a slightly different peripheral speed from it so that the relative movement between the edge of the scraper and the inner surface of the screen 2 is quite slow. The scraper is inclined with reference to the path of rotationof the body of thickened pulp on the inner surface of the screen and it therefore acts to plow up the pulp and force it slowly along the surface of the screen toward the end thereof opposite to the spider .3.

For the purpose of driving the scraper it is keyed or otherwise secured on a shaft 23 which is mounted inside the hollow shaft 8, suitable bushings 24 and 25 being interposed between the two shafts. A- pulley 26 is secured on the outer end of the shaft 23. It

is desirable to maintain 'a mat of thickenedfibre of appreciable depth on the inner surface of the screen in order to prevent the escape of pulp fibre, while at the same time allowing the surplus water to pass through the screen. For this reason it is preferable to drive the pulley 26 from a variable speed mechanism such as the double cone driving mechanisms very commonly used, so that the speed of rotation of the scraper can be ad justed with reference to the speed of the revolution of the drum: Assuming that the same peripheral speed, it will be evident that the scraper will produce no advancing movement of the thickened pulp. If, however, the scraper 21 is now speeded up, it will scrape the pulp from the inner surface of the screen and'advance said pulp toward the right-hand end, Fig. 1, of the screen at a rate depending uponthe difference inspeed between it and the screen 2. Consequently, by properly adjusting the relative speeds of the screen and scraper, the rate of the pulp discharging action can be regulated by the machine attendant,.and the thickness of the bed of pulp which is allowed to build up on the inner surface of the screen 2 can be controlled. In other words, this adjustment varies the ratio between the rate of deposit of the pulp on the screening surface and the rate of removal of the pulp from said surface and consequently, controls the duration of the thickening action upon a given body of pulp.

A driving mechanism suitable for this purpose is shown in Fig. 5 in which the screen drum pulley 12 is belted to the driving shaft 36, while the pulley 26 of the scraper shaft is driven from the shaft 36 through the variable speed drive 37.

As the scraper 21 continuously pushes the pulp past the right-hand end, Fig. 1, of the screen 2, it moves the pulp into the path of operation of a rotary ejector which also is secured fast on the shaft 23 and comprises several paddle-like blades 27, Figs. 1 and 3. This ejector revolves in a chamber formed in a casing member 28 which is bolted to the main casing 18, and it throws the thickened pulp through a discharge spout 30, Fig. 3, at the end of the machine opposite to the intake condnit 13. This material-may be discharged into a truck or upon a conveyor which will carry it away from the machine.

Instead of usinga scraper having a continuous surface as shown in Fig. 1, a scraper composed of sections may be used, such for example, as that shown in Fig. 2. This scraper consists of three members, each member being provided with a hub 31 and with two arms projecting therefrom, these, arms terminating in scraper blades 32. The blades are inclined and are so arranged that each one forces the thickened pulp along the inner surface of the drum into the path of operation of.the next succeeding blade, the final blade of the series moving the stock past the end of the screen and delivering it to the ejector 27. It should be noted that these scraper blades are not only inclined bodily with reference to the axis of the drum, but that their edges are also turned forward at an inclination to the path of rotation of the stock, so that they andpositively remove it from the screen. The

scraper shown in Fig. 2 is secured on the shaft 2 3,as 1s the scraper 21. screen 2 andscraper 21 are rotating at the Another form of scraper which may he used instead of the forms above described is shown in Fig. 4 at 34. This scraper is much like the scraper-.21, but has a slower pitch.

It will be observed that the machine is adapted to operate continuously. A constant supply of pulp is delivered through the intake conduit 13, the thickened pulp is discharged continuously through thelehute or spout 3) and the water flows oil through the pipe 20. While the machine is of the centrifugal type, it is extremely economical of power since the centrifugal force is created through the motion ofthe screening drum itself instead of by means of paddles or the like. Inasmuch as the scrapers do not come in contact with the surface of the screen, the wear on the screen and the danger of injury thereto are reduced to a minimum. The fact, also, that the thickness of the layer or mat of pulp on the inner surface of the screen can be regulatedv at will by the machine attendant and without stopping the machine are important practical advantages. In addition, the consistency of the stock discharged from the machine can be regulated by adjustment of the relative speeds of the scraper and drum. Since the water must escape not only through the screen but also through a layer of thickened pulp on the inner surface of the screen, even the finest fibres are strained out of the water so that there is practically no loss of fibre. It will be observed that the scrapers shown in Figs. 2 and at act only on the pul on or closely adj acent to the straining sur ace and consequently do not have any appreciable tendency to convey the unthickened pulp ,toward the discharge outlet. I

While I have herein shown and described the best embodiment of my invention that I have so far devised, it will be understood that the invention maybe embodied in other forms without departing from the spirit or scope thereof. For example, the drum need not be cylindrical but may be of conical or other form.

Having thus described my invention, what I desire to claim as new is:

1. In a pulp thickening machine, the combination of a screening drum adapted to be revolved rapidly to create centrifugal force for promoting the sereening action, means for conducting the materiakto be thickened into the interior of said drum, whereby the thickened pulp will collect upon the inner surface of said drum, and means revolving independently of said drum for advancing only the pulp on and closelyadjacent to the screening surfacetoward the outlet therefor.

2. In a pulp thickening machine, thecombination of a screening drum adapted to be, revolved rapidly to create centrifugal force for promoting the screening action, means for conducting the material to be thickened into the interiorof said drum, whereby the thickened pulp will collect upon the inner surface of said drum, and means for con tinuously removing said thickened stock 4 from the inner surface of said drum but operable to permit said stock to build up on said surface to a depth adjustable by the machine attendant.

3. In a pulp thickening machine, the combination of a screening drum adapted to be revolved rapidly to create centrifugal force for promoting the screening action, means for' conducting the material to be thickened into the interior of said drum, whereby the thickened pulp will collect upon the inner surface of said drum, a scraper in said drum having an edgeportion located close to the inner'surface of the drum, said edge portion being inclined with reference to the plane of rotation of the drum, and means for revolving said scraper at a different speed from that of the drum, whereby said scraper is operative 'to advance the thickened pulp along the surface of the screen, said scraper being constructed and mounted to leave substantially undisturbed the pulp in said drum and approaching the screen but which is still spaced therefrom by a substantial distance.

4. In a pulp thickening machine, the combination of a screening drum adapted to be revolved rapidly to create centrifugal force for promoting the screening action, means for conducting the material to be thickened into the interior of said drum, whereby the thickened pulp will collect upon the inner surface of said drum. rotary means for advaneing the thickened pulp along the surface of said drum toward one end thereof, and a rotary ejector to which the pulp is delivered by said advancing means. 7 In a pulp thickening machine, the combination of a screening drum adapted to be revolved rapidly to create centrifugal force for promoting the screening action, means for delivering a continuous stream of material to be thickened into one end of said drum, whereby'the thickened pulp will collect upon the inner surface of the drum, a rotary scraper inside said drum for continuously advancing said thickened pulp toward the opposite end of said drum, and means to which the pulp is delivered by said scraper for ejecting the pulp from the machine.

6. Ina pulp thickening machine, the combination of a screening drum, a hollow shaft supporting said drum for rapid rotation, a rotary scraper mounted inside said drum in operative relationship to the inner surface thereof for removing thickened material from the screening surface of the drum, and ashaft mounted within said hollow shaft and. supporting said scraper.

7. In a pulp thi kening machine,;.the combination of a screening drum,.="a hollow shaft supporting said drum for rapid rotation, a

rotary scraper mounted inside said drum and operative to advance the thickened pulp along the inner surface of said drum toward one end thereof, a rotary ejector to which the thickened stock is delivered by said scraper, and a second shaft mounted inside said hollow shaft and supporting said scraper and ejector.

8. In a pulp thickening machine, the combination of a screening drum adapted to be revolved rapidly, a conduit for conducting walls and a casing in which said drum is mounted for rotation.

' 9. In a pulp thickenin I bination of a screening drum adapted to be revolved rapidly, a conduit for conducting material to be thickened into one end of' said drum, said drum having an annular chamber in the latter end thereof and at the end of itsscreening surface to receive said material, and a distributor for directing the stock outwardly into said chamber, said chamber having walls inclined toward the screening surface of the drum whereby the centrifugal action of the drum on said material will cause the material to flow on to the screening surface 'ofthe drum.

10. In a pulp thickening machine, the combination of a screening drum adapted to be revolved rapidly, a conduit for conducting material to be thickened into one end of said drum, said drum having an annular chamber in the latter end thereof and at the end of its .screening surface to receive said material, a distributor for directing the stock outwardly into said chamber said chamber having walls inclined toward the screening surface of the drum wherebythe centrifugal action of the drum on said material will cause the material to flow on to the screening surface of the drum, and means for contiI1- uously moving the thickened material along the inner screening surface of the drum and forcing it out of the drum at the end thereof opposite to said chamber.

11. In a pulp thickening machine, the combination of a screening drum having a spider at one end thereof, a shaft on which said spider is mounted, means supporting said shaft for rotation, a conduit for conducting material to be thickened to the spider end of said drum, a distributor for directing said material outwardly at said end toward the' screening surface of the drum, and a casing in which said drum is mounted for rotation.

12. In a pulp thickening machine, the combination of a screening drum adapted to be revolved rapidly to create centrifugal force for promoting the thickening action, means for conducting the material to be thickened into the interior of said drum, whereby the thickened pulp will collect upon the inner surface of the drum, a scraper in said drum substantially open at its central portion and having an edge portion located close to the machine, the com-.

inner surface of the drum, said edge portion being inclined with reference both to the plane of rotation of the drum and to the surface of the said drum, and means for revolving said scraper relatively to the drum, whereby the scraper is operative to advance the thickened pulp along the surface of the screen.

13. That improvement in processes of thickening pulp which consists in producmg the thickening action centrifugally upon the inner surface of a rapidly revolving screen-- ing drum, and forcing the thickened pulp along the surface of said drum toward one end thereof. I

14. That improvement in processes of thickening pulp, which consists in flowing a stream of pulp continuously into a rapidly revolving screening drum, causing said pulp to revolve rapidly-prior to and as it flows on to the screening surface of said drum, whereby surplus water in the pulp will be forced through said screening surface by centrifugal action and'the thickened pulp will collect upon the inner surface of the screen, and continuously removing the thickened pulp from said surface.

15. That improvement in processes of thickening pulp which consists in producing the thickening action centrifugally upon the inner surface of a rapidly revolving screening drum, forcing the thickened pulp along the surface of said drum toward one end thereof, andcontrolling the duration of the thickening action upon a given body of pulp by varying the ratio between the rate of deposit of the pulp on the screening surface and the rate of removal of the pulp from said surface.

ANTON JOSEPH HAUG.

CERTIFICATE OF CORRECTION.

Patent No. l,756,.l94. I Granted April29, 1930, to

' ANTON JOSEPH HAUG.

It is hereby certified that error appears in the printed specification of the above numbered "patent requiring correctionas follows: Page 1, line 5), for the word "of" second occurrence read "or"; page 3, lines 39, 51, 64, 85 and. 97,

claims 1, 2, 3, 4 and 5, respectively, for the word "screening" read "thickening"; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 20th day of May, A. D. 1930.

M. J. Moore, (Seal) Acting Commissioner of Patents. 

